半金屬銻化鎵/砷化銦系統中傳輸及光學性質研究

Abstract

Semi-metallic GaSb/InAs system has attracted much attention due to its unique band alignment. In this thesis, we report the Hall effect and photoluminescence studies of such a system. In the Hall effect measurement, it was found that the electron concentration in the InAs decreases with decreasing temperature. Three activation energies (Ea1, Ea2 and Ea3) were obtained. Ea2 obtained from the cross over region (about 30 K to 50 K) is smaller than 1 meV, and it is tentatively attributed to the binding energy of the spatially exciton in this system. We found that our transport results at low temperature are consistent with the Bose-Einstein Condensation (BEC) behavior which theoretical prediction proposed by J. F. Jan and Y. C. Lee. Using self-consistent variational approach to model the structure, we are able to estimate the electron n (in the InAs layer) and hole p (in the GaSb layer) densities. In the photoluminescence (PL) measurement, temperature and power dependence of photoluminescence emission were performed and two main peaks (798meV and 773meV) corresponding to the transitions in GaSb layer were observed. From the Arrhenius plots of the integrated intensities, activation energies were obtained. We suggest that the 798 meV transition is a band-acceptor transition instead of a bound excition- neutral acceptor (BE) transition which other authors have proposed in bulk GaSb. We’ve also observed the integrated PL intensity of 773meV peak (e-Å) tends to saturate with raising laser power.